Detective Superintendant John Stewardson, who led the operation from the UK, said: "I am confident this operation has targeted the hard core of individuals engaged upon Internet paedophile activity around the world".

Bob Packham, deputy director general of the UK's National Crime Squad, said Operation Cathedral had opened a new chapter in policing the Internet.

He said he believed that no other operation had ever brought together so many law enforcement agencies.

"Through this investigation we have recovered well in excess of 100,000 indecent images of children," he said.

"It has been a difficult and distressing investigation and I hope that our actions have prevented further abuse of children across the world."

'Horrendous legacy'

The operation began when officers with Sussex police, south-east England,
received a tip-off from US Customs officers which led them to the "Wonderland Club" network.

Aided by the National Criminal Intelligence Service, they drew in Interpol and police forces across Europe when it emerged that there was almost constant international contact over the Internet between members of the ring.

Initial investigations led all the police forces to meet during the summer at Interpol's Paris headquarters.

Det Supt Stewardson said the "Wonderland Club" paedophiles had left a "horrendous legacy" of abuse among their victims.

"There are people who simply exchanged material and some who produced it," he said.

"We have got one producer in the UK who was part of this group.

"The children abused were of both sexes and some it would appear were as
young as two, although we don't know who these children are yet.